To investigate the relationship between farming exposures and asthma, we have developed a case-cohort study within a large cohort of farmers -- the Agricultural Health Study. This study follows up findings regarding the association between correlates of exposure to pathogen associated molecular patterns (such as endotoxin) and various questionnaire-based asthma and atopy phenotypes. It is also designed to follow-up findings based on questionnaire data of positive associations between pesticide exposures, especially organophospates, and questionnaire-based asthma phenotypes. To confirm and better understand these associations, objective measures of asthma and atopy phenotype are needed along with more detailed and objective exposure assessment. This study builds upon the Agricultural Health Study, a large cohort of farmers and their spouses in Iowa and North Carolina. We identified presumptive cases of asthma and non cases from the third phase of cohort follow-up and made home visits on eligible subjects. The Lung Health Study was launched on Feb 4, 2009. Field work ended September 30, 2013 and telephone interviews ended on November 15, 2013. We completed home visits with 3,255 people and 3,200 (98%) completed telephone interviews following their home visit. There were 46 subjects who were partial participants (self-collected dust and saliva) and 44 (96%) completed telephone interviews following the return of their samples and forms.